Precise voltage monitoring (e.g., +/−1%) is needed in various electrical devices (e.g., safety devices). One example circuit used for voltage monitoring is a comparator. Over time, the threshold voltage of transistors used in a comparator may shift. For example, if the threshold voltage of transistors used in a comparator shift due to positive bias temperature instability (PBTI) or negative bias temperature instability (NBTI), the results is a loss of accuracy in the comparator over time.